Abstract: [Objective] This study aims to investigate the effects of systemic acquired resistance on growth and reproduction of gypsy moth (Lymantria dispar) after locally spraying exogenous jasmonic acid (JA) on Larix olgensis seedlings.[Method] Three concentrations of jasmonic acid(0.01,0.10 and 1.00 mmoL·L^-1)plus a water control (CK) were sprayed on L. olgensis seedlings with partial or whole plant, respectively; the growth rates and the egg numbers of gypsy moth that fed on these seedlings were recorded, and their detoxification enzyme activities were also investigated.[Result] The average body mass of 3rd to 6th instars of gypsy moth larvae from the treatment groups was all lower than that of water control group (CK) regardless of the spray method (whole or partial). Among them, the body mass of the 3rd to 6th instar larvae on seedlings treated with 1.0 and 0.1mmol·L^-1 concentrations of both sprays, and of 5th to 6th instar larvae on seedling with 0.01(partial) and 0.01 mmol·L^-1 (whole) treatments was significantly lower than that of CK (P<0.05). The gypsy moth larval survival rates, pupal mass, and the laying egg number in all treated groups were also lower than those of CK. The pupal mass and the egg number in the all treated groups except for 0.01 mmol·L^-1(whole)treatment were significantly lower than those of CK (P<0.05). At the same JA concentration, partial spays had similar inhibiting effects as did the whole sprays on the larval growth and the egg number. Partial spray with 1 mmol·L^-1 JA concentration showed stronger inhibiting effect than the other two concentrations. The ACP and AKP activity of the 3rd instar larvae and the AKP, the SOD and POD activity of the 4th instar larvae in 0.01 mmol·L^-1 (partial) treatment groups were significantly higher than those of CK (P<0.05). The activity variation patterns of these protective and detoxifying enzymes of 0.01 mmol·L^-1 (partial) treatment groups were similar to those of 0.01 mmol·L^-1 (whole) treatment groups.[Conclusion]Spraying JA on local parts of L. olgensis seedlings (partial spray) can increase its induced resistance against insects, and inhibit the growth and reproduction of gypsy moth, and achieve the same inductive effects as spraying on the entire seedling. On the other hands, gypsy moth larvae in turn can develop strategies to overcome larch inducible resistance through improving the activities of their protective and detoxification enzymes.

Key words: jasmonic acid(JA), Larix olgensis, Lymantria dispar, locally spraying, whole spraying